Table of Contents:
- General Overview of Measurement & programming principles with photoLab® 7000 Seriesie
- Programming of Chlorophyll method: step by step
- Wine quality factors: Colour intensity and nuance
- Overview of sugar determination principle with enzymatic test kits: Glucose, Sucrose, Fructose
Programms and Programming:
- Concentrations measurements:
Programmed methods for commercial test kits User calibration curves e.g. for Uranine
- Multi-step measurements:
Chlorophyll methods for environmental analytics, Food (nutrition), R&D…
- Enzymatic test kits
available from various manufacturers, complex handling eased by (user-defined) programs
- Multi-wavelength measurements
e.g. wine colour
Extense Programming options

Programming with photoLab® 7000

Operators, Variables, Conditions…
R = Result
K = Variable in formula, to be defined
A = Absorption A xxxnm
Same absorbance at different steps:
measurements at same wavelength: A xxxnm_2; A xxxnm_3…
F = Key for easy operation:

Operators via F2
F1: Back
F4: Next
Variables via F3 (Axxxnm, K1, K2…)
F4: Next
Chlorophyll measurement is needed in many applications:
- Environmental Analysis
- Algae content in food & beverage industry
- Required procedures vary according to application field!

Easy programming according to application requirements
- Sample preparation according to standard methods:
Chl is extracted, and a small volume of the extract is measured photometrically
- The determination of the Chlorophyll is done by measuring the difference of the absorbance before and after adding HCl.
- The final formula of Chlorophyll take sample and extraction volume into the automatic calculation.
Programming Chlorophyll Measurement:


Here, it is important to indicate the sequence of measurement steps by assigning an index to the absorbance measurement (2, 3…). Subsequently a clear description to each single step can be entered for user-guidance on display.

Using F3 will show an R for Result which can be defined: e.g. for R<0 wrong the resulting display ---- mg/l
To correct condition, use back space until back to left screen
Wine Colour: An Important Quality Factor
Colour Measurement in Beverage / Wine Industry …
… is important for:
- Wine growers
- Third party bottlers’ income quality control.
Photometric colour measurement offers:
- Accuracy and comparability (versus human eye, comparator …)
- Reproducibility
Bottlers need several routine testings besides coulor:
- Testing Water parameters, sugar content, …
- Turbidity (in many other beverages)
- COD before disposing water to municipal wastewater plant
Wine Colour = Multi-λ measurement
Wine characterization by colour
Colour Intensity = Sum
Absorbance measurement @ λ 420nm, 520nm and 620nm
Abs420 for yellow/orange/ocker
Abs520 for red
Abs620 for blue (not always included)
R = Abs420 + Abs520 +Abs620
R = Abs420 + Abs520
Colour nuance
Ratio of brown/red nuances < 0,8 violet, 0,8-1,2 red, > 1,2 orange
R = Abs420 /Abs520
Determinations of Sugar (Glu…) with enzymtic test kits, e.g. with
Understanding Enzymtic Test Kits?
Sugar (D-Glu, D-Fru, Sucrose etc.) are important parameters in Wine, Food & Beverage
- Test kits are based on enzymatic reactions for many substances
- Enzymes are specific to chemical reactions and substances (substrates)
- Some tests offer multi-step measurements for determinations of individual sugar molecule concentration such as Sucrose, Glu and Fru
- Enzymatic test kits are gradually replacing other standard methods
- Are accepted by many International Organisations in Food & Beverage
- Enzymes „co-operate“ with metabolistic „energy provider“ (ATP) and Co-enzymes offering a Redox system, here NAD+/NADH and NADP+/NADPH
The Hub: NAD+/NADH co-enzyme:
NAD+/NADH and NADP+/NADPH is a standard step in enzymatic reactions. In reduced form, these redox systems show a peak at 340 nm.

Scheme of Suc, Glu, Fru determination:

Glutotal: Σof Glufree and Glubound
Suc / Fru: Glufree determination before and after „cracking“ of Sucrose
Enzymatic Test Kits …
…. provide:
- all necessary information on substances to enter formula
- all enzymes needed
- all co-enzymes such as NADP+, ATP etc.
- AQA material
The transfer of reaction into a simplified photometric routine may need several steps and formulae.
Here you can download the whole article as PDF:
